Commutator



1944- L. F. HEMPHILL. 2,357,111

COMMUTATOR Filed Dec. 5, 1942 Inventor: Lawrence F. Hemphill,

/V H Hi e attorney Patented Aug. 29, 1944 COMMUTATOR Lawrence F.Hernphill, Fort Wayne, Ind., assignor to General Electric Company, acorporation of New York Application December 5, 19, Serial No. 467,959

3 Claims.

My invention relates to commutators for dynamo-electric machines.

An object of my invention is to provide improved and simplifiedcommutator constructions.

Further objects and advantages of my invention will become apparent andmy invention will be better understood from the following descriptionreferring to the accompanying drawing, and the features of novelty whichcharacterize my invention will be pointed out with particularity in theclaims annexed to and forming part of this specification.

In the drawing, Fig. 1 is a side elevational view. partly broken away,illustrating an embodiment of my invention; and Fig. 2 is a perspectiveview of the insulating support shown in Fig. 1.

Referring to the drawing, I have shown an embodiment of my improvedcommutator wherein an insulating sleeve supporting element I is mountedon a shaft H and is formed with a plurality of axially extending groovesI! which extend from adjacent the outer end of the sleeve l0 inwardly ofthe support and in an outer angularly extending surface I! of anoutwardly extending insulating shoulder element ll. The shoulder I4 isformed at an angle to the axially extending sleeve portion l0 and stopsI! are formed at the end of each of the slots l2 at the end of theinsulating support opposite the shoulder II. The commutator is formed ofa plurality of segments of electrically conductive material whichinclude axially extending brush seat portions it and angularly extendingportions H which are arranged in the portions of the slots I! in thesleeve Ill and the shoulder ll, respectively. A clamping ring I! ofinsulating material is arranged over the commutator segments and ispressed over the axially extending portions thereof to a positionadjacent the shoulder I4 and biases the segments into engagement withthe insulating support for retaining the commutator in assembledrelationship. With such a construction, centrifugal force will act onthe angularly and axially extending portions of each commutator segment,as indicated by the arrows a and b, repsectively. Since the angularsegment portion extends outwardly from the axial segment portion, theradius c at which centrifugal force acts on the angular portion isgreater than the radius d for the axial portion. Therefore, if theweight of the angular portion is substantially the same or greater thanthe weight of the axial portion, the centrifugal force acting on theangular segment portion on rotation of the commutator will be greaterthan the centrifugal force acting on the respective segment axialportion. The two portions of each commutator bar may be formed of such asize that the weights thereof are substantially the same, butthis is notessential. The radius 0 of the center of gravity or the hypotheticalpoint of action of centrifugal force on the segment angular portion issubstantially greater than the radius d of the center of gravity orpoint of action of centrifugal force on the segment axial portion, and,therefore, the centrifugal force a on the segment angular portion willtend to be greater than the centrifugal force b on the segment axialportion. A consideration of force moments due to centrifugal force onthe segment portions indicates that a force moment acts on each of thesegments it about the clamping ring is as a pivotal retainingring. Onrotation of the commutator. the segment angular portion I1 is acted onby the centrifugal force a acting through a moment arm e and the segmentaxial portion is acted on by the centrifugal force b acting through amoment arm f. This produces a centrifugal force moment ae for thesegment angular portion and a centrifugal force moment bf for thesegment axial portion. In order to assist in maintaining the axialsegment portions firmly against the insulating supporting sleeve ID, thesegment angular portions on one side of the retaining ring areconstructed of such a size and arranged to extend at such an angle thatthe centrifugal force moment ae thereon about the clamping ring ll isgreater than the centrifugal force moment bl on the segment brush seataxial portion, thereby tending to rotate the segment about the ring ISin a counterclockwise direction as viewed in Fig. 1. Thus, centrifugalforce will tend to hold the commutator in assembled relationship ratherthan tending to cause it to fly apart.

While I have illustrated and described a particular embodiment of myinvention, modifications thereof will occur to those skilled in the art.I desire it to be understood, therefore, that my invention is not to belimited to the particular arrangement disclosed,.and I intend in theappended claims to cover all modifications which do not depart from thespirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A commutator including an insulating support. a plurality ofcommutator segments arranged on said support, and pivotal retainingmeans arranged intermediate the ends of said segments providing a brushseat portion and a portion on the other side of said retaining means forsecuring said segments on said support, the weight and center 0! gravityof said other side segment portions being such relative to that of saidbrush seat segment portions that the moment oi said other side portionsabout said securing means is greater than the moment oi said brush seatportions thereabout.

2. A commutator including an insulating support having a shoulderthereon extending outwardly at an angle, a plurality of commutatorsegments having a portion of each extending axially on said support anda portion of each iormed at an angle to said axially extending portion,and means for securing said segments on said support with said segmentangular portions clamped against said shoulder. the weight and center ofgravity of said segment angular portions being located such that themoment thereof about said securing means is greater than the moment 01said axially extending segment portions thereabout.

3. A commutator including an insulating sleeve assmn support having ashoulder thereon extending outwardlyatananglaapluralityoispaeedapartgrooves in said sleeve and shoulder. a plurality oi commutator segmentshaving a poruon oi eachextendingsubatantiallyaxiallyinsaidsieeve groovesand a portion 0! each formed at an angle to said axially extendingportion. and means including a clamping ring arranged over said segmentsadjacent said shoulder for securing said segments in said grooves onsaid supporting sleeve with said segment angular portions clampedagainst said grooves in said shoulder. the weight and center of gravityof said segment angular portions being such relative to the weight andcenter of gravity 0! said axially extending portions that the moment ofsaid anaularly extending portions about said clamping ring is greaterthan the moment of said axially extending segment portions thereahout onrotation 01 said commutator.

